Two-dimensional strongly coupled plasma on a solid surface

A simple two-dimensional strongly coupled one-component plasma system has b een developed using charged metal balls. The small stainless steal balls ar e charged up using high voltage on a silicon wafer and the random kinetic e nergy of the balls is given by the oscillation of the wafer, which is contr olled by the input power from a speaker placed underneath the wafer. The pa ir correlation function and the diffusion coefficient at several Coulomb pa rameters are measured to study the transition between the liquid and solid phases. In the liquid phase, a coherent mode in the density fluctuation is observed.